Organic Electro-luminescent display (OLED) devices have been widely used due to their features such as light weight, low power consumption, high response and high resolution.
An OLED display device includes an array substrate and a package substrate for packaging the array substrate. The array substrate includes an anode, a cathode and a luminescent layer between the anode and the cathode. For a top-emitting OLED, when light emitted from a luminescent layer is emitted outside from a cathode side, the thickness of the cathode is thin so that the light can pass through the cathode. Thus, the cathode has the largest resistance in the whole OLED structure.